lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20160609133529.GA5400@rkaganb.sw.ru>
Date:	Thu, 9 Jun 2016 16:35:29 +0300
From:	Roman Kagan <rkagan@...tuozzo.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
CC:	<linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>,
	<mnghuan@...il.com>, <luto@...nel.org>
Subject: Re: [PATCH] pvclock: introduce seqcount-like API

On Thu, Jun 09, 2016 at 02:47:54PM +0200, Paolo Bonzini wrote:
> On 09/06/2016 14:43, Roman Kagan wrote:
> > On Thu, Jun 09, 2016 at 01:23:23PM +0200, Paolo Bonzini wrote:
> >> The version field in struct pvclock_vcpu_time_info basically implements
> >> a seqcount.  Wrap it with the usual read_begin and read_retry functions,
> >> and use these APIs instead of peppering the code with smp_rmb()s.
> >> While at it, change it to the more pedantically correct virt_rmb().
> >>
> >> With this change, __pvclock_read_cycles can be simplified noticeably.
> >>
> >> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> >> ---
> >>  arch/x86/entry/vdso/vclock_gettime.c | 25 +++++------------------
> >>  arch/x86/include/asm/pvclock.h       | 39 +++++++++++++++++++++---------------
> >>  arch/x86/kernel/pvclock.c            | 17 ++++++----------
> >>  3 files changed, 34 insertions(+), 47 deletions(-)
> > [...]
> >> --- a/arch/x86/include/asm/pvclock.h
> >> +++ b/arch/x86/include/asm/pvclock.h
> > [...]
> >> @@ -69,23 +87,12 @@ static inline u64 pvclock_scale_delta(u64 delta, u32 mul_frac, int shift)
> >>  }
> >>  
> >>  static __always_inline
> >> -unsigned __pvclock_read_cycles(const struct pvclock_vcpu_time_info *src,
> >> -			       cycle_t *cycles, u8 *flags)
> >> +cycle_t __pvclock_read_cycles(const struct pvclock_vcpu_time_info *src)
> >>  {
> >> -	unsigned version;
> >> -	cycle_t offset;
> >> -	u64 delta;
> >> -
> >> -	version = src->version;
> >> -	/* Make the latest version visible */
> >> -	smp_rmb();
> > 
> > This is on top of Minfei's patch, right?  It isn't in Linus' tree yet so
> > I wonder if it makes sense to merge the two patches into one.
> > 
> > Will you post it to stable, too?
> 
> Not this one, because Minfei's patch is enough to fix the bug, but I do

Has it landed in any public tree?  I'm unable to find any.  There
appears to be another version of the patch on the list, so I'm confused.

Roman.

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ